UK experiments with Covid vaccine mix

LONDON – A trial is underway in the UK to explore whether the use of different Covid-19 vaccines for the first and second doses works in an attempt to make national vaccination programs more flexible.

The trial, led by Oxford University and led by the National Immunization Program Evaluation Consortium, will assess the feasibility of using a different vaccine for the initial “first” vaccination to the “booster” vaccine. tracking.

The study is expected to help policymakers understand whether mixing different Covid vaccines could be a viable way to increase the flexibility of vaccination programs and whether it could even provide better protection.

“If we demonstrate that these vaccines can be used indiscriminately at the same time, this will greatly increase the flexibility of vaccine delivery and could provide clues on how to increase the breadth of protection against new virus strains,” Matthew Snape said. , chief researcher said Thursday about the trial and associate professor of paediatrics and vaccinology at Oxford University.

The trial, which is formally known as the “COVID-19 Heterologous Prime Boost study” but has been dubbed the “Com-Cov” study, will recruit more than 800 volunteers aged 50 and over in England to assess the four different combinations of booster vaccination.

You will try a first dose of the Oxford-AstraZeneca vaccine followed by an increase with the Pfizer-BioNTech vaccine or with an additional dose of the Oxford-AstraZeneca vaccine. The research will also examine a first dose of the Pfizer-BioNTech vaccine followed by an increase with the Oxford-AstraZeneca vaccine or an additional dose of the Pfizer-BioNTech vaccine.

These will be evaluated at two different dosing schedules: within a four-week interval to give a provisional reading of provisional data and within a 12-week interval. This latest dosing interval is the UK’s current vaccination policy: a delay in the second dose means more people can get their first vaccines sooner rather than later in the midst of a tight supply of vaccines.

While the policy has been seen to be controversial, some experts are concerned that it could make vaccines used in the UK less effective; so far, only Oxford-AstraZeneca and Pfizer-BioNTech candidates are used, which will be added to the vaccine basket that will be used in the Modern shot in the spring.

However, the University of Oxford on Wednesday published a study showing that a 12-week delay between the first and second doses of AstraZeneca jab increases the effectiveness of the vaccine.

The researchers found that the shot was 76% effective in preventing symptomatic infection for three months after a single dose and that the efficacy rate increased to 82.4% when there was at least a 12-day interval. weeks before the second dose. When the second dose was administered less than six weeks after the first, the efficacy rate was 54.9%.

In the latest “Com-Cov” study, researchers will collect blood samples from trial volunteers and monitor the impact of different dosing regimens on participants’ immune responses, as well as look for additional adverse reactions to new combinations. of vaccines.

The study will run for 13 months and has been supported by £ 7 million ($ 9.5 million) in government funding from the Vaccines Taskforce, which was set up by the UK last April to coordinate the efforts to investigate and produce a coronavirus vaccine.

Professor Snape said the study was “tremendously exciting”, before adding that it would “provide vital information for vaccine deployment in the UK and around the world”.

Richer countries are vying to vaccinate as many people as possible than national closures, with the goal of limiting the spread of infections and preventing hospitals from being invaded and damaging economies.

The UK has been hit hard by the pandemic and has seen an increase in cases in the winter, helped by a more virulent variant of the virus that emerged in the south-east of England and has now become a dominant strain. in the country.

The UK currently has the fourth largest number of cases in the world, with more than 3.8 million confirmed infections, according to a Johns Hopkins University account, and has recorded 109,547 deaths.

Earlier last year, the UK government was quick to order coronavirus vaccines from several manufacturers and approved the vaccines currently in use. Its vaccination program has been widely praised for its agility and reach, and aims to vaccinate 15 million people in its four main priority groups, including health and care workers, the elderly and the elderly. over the age of 70 and anyone who is considered extremely clinically vulnerable. mid-February.

The latest government data, as of Wednesday, shows that just over 10 million people have had the first dose of vaccine and just under 500,000 have also had a second dose. The Oxford-AstraZeneca vaccine, which is produced in Britain, makes up the bulk of the UK vaccination program.

The deputy medical director and lead author of the study, Professor Jonathan Van-Tam, said the research could even show that alternating vaccines could increase the level of antibodies needed to fight potential Covid infection. 19.

“It is even possible that by combining vaccines, the immune response can be improved by giving even higher levels of antibodies that last longer; unless evaluated in a clinical trial, we will not know. This study will give us more information about how we can use vaccines to keep up with this nasty disease, ”he said.

UK vaccination minister Nadhim Zahawi told the BBC on Thursday that, for now, the country’s vaccination program would continue as normal: “For now we will not change anything,” Zahawi told the ‘Avui’ program.

“If you had a Pfizer BioNTech vaccine for your first dose, you will have a Pfizer BioNTech vaccine for your second. If you had Oxford-AstraZeneca, you will have Oxford-AstraZeneca for your second dose.”